The present invention relates generally to the interior cleaning of a tubular member and more particularly to the cleaning of the off gas cooler of a vitrification unit.
Vitrification plants have been designed to solidify radioactive waste resulting from nuclear fuel reprocessing. A vitrification unit mixes radioactive and other waste with the components of borosilicate glass, melts the mixture at high temperatures for periods of time, and pours it into stainless steel canisters for storage. Due to the radiation and high temperatures, most major components in the unit are remotely removable using only crane mounted equipment. All piping and electrical connections to these components also use crane removable jumpers. All operations are remotely monitored to protect workers and prevent the release of pollutants. In addition to shield windows, operations are monitored by camera.
Any radioactive emissions from the heated mixture in the vitrification unit are drawn by vacuum into the Off Gas Treatment system. The In-cell section of the system can consist of a film cooler, submerged bed scrubber with mist eliminator, and mist eliminator preheaters. Gaseous emissions are quenched, scrubbed to remove radioactive particulate matter, then passed through the mist eliminator to remove liquid droplets. Gases are then heated and passed through the high efficiency mist eliminators to remove submicron particulate matter. From the In-cell treatment section, gases flow into the Ex-cell treatment section for filtration and catalytic reduction.
Substantial operational difficulties have been encountered due to radioactive particulate matter precipitating in the In-cell Off Gas Treatment piping. Plugging of the pipes has resulted in premature termination of a rim, with increased risk of release of emissions and endangerment of workers. There is a need to remove particle build-up during operation to avoid premature termination of operations which the present invention addresses.